rollout
noun [ C ] uk/ˈrəʊlˌaʊt/ us/ˈroʊlˌaʊt/
首次提供（产品或服务）
the act of making something, especially a product or service, available for the first time
Since its rollout in fall of 1999, PayPal has gained millions of members. 自从1999年首次提供使用以来，PayPal已经吸引了以百万计的用户。
首次展示（提议，法律或信息）
A rollout of proposals, laws, or information is the first time they are made known to the public.